The invention relates to a diaphragm pump which has a pump diaphragm in at least one pump head, which pump diaphragm is clamped by way of a clamping zone which is arranged on its outer circumference between two housing parts of a pump housing and defines a delivery space between itself and a pump head part, and which encloses, in a central zone, a diaphragm armature, the annular zone which is arranged adjacently to the clamping zone being configured as a guide zone which, in the unloaded state of the pump diaphragm, is curved convexly and projects into the delivery space.
The previously known diaphragm pumps have at least one pump head which is assigned a working or pump diaphragm. The outer circumferential edge region of said working or pump diaphragm is configured as a clamping zone, by way of which the working or pump diaphragm is clamped between two housing parts of the pump housing in such a way that the working or pump diaphragm defines a working or delivery space between itself and a pump head part. A metal diaphragm armature is vulcanized in regions into a central diaphragm zone, which diaphragm armature is connected to a reciprocating drive on its side which faces away from the working or delivery space. With the aid of said reciprocating drive, the working or pump diaphragm of the at least one pump head can be set into an oscillating reciprocating movement.
Various diaphragm embodiments are already known previously as working or delivery diaphragms. Thus, at the top dead center of the reciprocating movement, what is known as the shaped diaphragm is capable of bearing positively against the dome-shaped working or delivery space of the associated diaphragm pump. Firstly, working or pump diaphragms of this type have to be of sufficiently elastic configuration, in order to withstand the forces which act on them as a result of the tumbling movement of the diaphragm during the pump operation; at the same time, said working or pump diaphragms also have to be sufficiently dimensionally stable, in order not to be deformed in a manner which reduces performance by the opposed pressure forces which act on the opposite diaphragm sides during the pump operation. What are known as structured diaphragms have therefore also been produced which, on their diaphragm side which faces away from the working or pump space, have structures which are formed by concentric webs and radial ribs and permit a defined tumbling movement of the structured diaphragms during the pump operation.
EP 1 460 270 A2 has already disclosed a diaphragm pump which is operated with compressed air and which therefore does not have an eccentric as reciprocating drive, which eccentric would be provided for the oscillating reciprocating movement of the pump diaphragm. On opposite sides of its pump housing, the previously known diaphragm pump which is operated with compressed air has in each case one pump diaphragm which is clamped sealingly in the pump housing by way of its outer edge region which is configured as a clamping zone. The pump diaphragms have a central zone, into which a diaphragm armature is formed integrally, the diaphragm armatures of the pump diaphragms which are provided on both sides being connected to one another via a connecting web. A convexly curved guide zone which projects into the adjacent working space is configured between the central zone and the clamping zone. Since, however, the diaphragm pump which is already known from EP 1 460 270 A2 does not have an eccentric drive, the convexly curved annular zone of the previously known diaphragm pump also cannot and does not have to roll on an annular zone of the pump head. Further zones are not configured in the pump diaphragm which is used in EP 1 460 270 A2.
U.S. Pat. No. 5,634,391, EP 1 058 005 A2 or DE 94 03 103 U1 has already disclosed pump diaphragms for a diaphragm pump which have a convexly curved annular zone which projects into the working space between their outer edge region which serves as a clamping zone and a central region. Since the abovementioned documents are concerned merely with the design of the pump diaphragm, said documents do not mention in greater detail whether the previously known pump diaphragms are intended to bear with said convexly curved annular zone against that inner wall of a pump housing which defines the delivery space and, in particular, are intended to roll thereon during the reciprocating movement. Further annular zones are also not configured in the pump diaphragms according to the previously known documents.